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Pulmonary function test

Pulmonary function test

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Pulmonary function test

  1. 1. Pulmonary Function Test
  2. 2. DR S RAGHU M.D., ASST PROF DEPT. T B & CD GUNTUR MEDICAL COLLEGE GUNTUR Dr s. raghu m.d., Associate professor Department of TB & CD R I M S medical college ONGOLE
  3. 3. •11,000 Lts air every day • Patency of airways VENTILATION PERFUSION • 11,000 Lts blood every day • Lung Volume available • Diffusibility across membrane 550 L of O2 consumes every day
  4. 4. THE STETHOSCOPE • Presence or absence of air entry • Presence of airway narrowing •Cavities in the Lung BUT NO REAL OBJECTVE MEASURE OF LUNG FUNCTION Laennec’s Stethoscope
  5. 5. EARLY MEASURES OF LUNG FUNCTION
  6. 6. How strong are your lungs?
  7. 7. Volume of displaced water = Volume of air in balloon (Stephen Hales, UK, 1727) MEASURING LUNG VOLUMES WITH A BALLOON AND THE ARCHIMEDES PRINCIPLE
  8. 8. MEASURING LUNG VOLUMES WITH A BALLOON AND THE ARCHIMEDES PRINCIPLE
  9. 9. DISCOVERY OF THE SPIROMETER Sir John Hutchinson, 1846 Hutchinson J, The Lancet 1846; 1: 630-632 Vital capacity - More sensitive to detect Tuberculosis than auscultation - Can predict life expectancy. Suggested this test for routine life insurance cover.
  10. 10. spirometry • John Hutchinson (1811-1861)—inventor of the spirometer and originator of the term vital capacity (VC). • “Spirometry is a physiological test that measures the volume of air an individual inhales or exhales as a function of time. (ATS / ERS 2005 ) . • Simple, office-based
  11. 11. • Volume Displacement-based • Flow sensor-based TYPES OF SPIROMETERS
  12. 12. VOLUME DISPLACEMENT SPIROMETER Water seal, Rolling Piston, Bellows
  13. 13. Pneumotachograph (Changes in Pressure) Anemometer (Changes in temperature) Turbine (Changes in number of revolutions) Ultrasonic (Ultrasound transit time analysis) FLOW-SENSOR BASED SPIROMETER
  14. 14. Introduction • The term encompasses a wide variety of objective methods to assess lung function. They Provide quantifiable, reproducible measurement of lung function . • They do not act alone. • They act only to support or exclude a diagnosis. • A combination of a thorough history and physical exam, as well as supporting laboratory data and imaging will help establish a diagnosis.
  15. 15. The various components of pulmonary function tests • Tests for ventilation : spirometry with helium dilution technique & body plethysmography. • Tests for diffusion : diffusion capacity for CO (DLCO) . • Tests for ventilation / perfusion : V/Q scan , nitrogen wash out test. • Exercise testing :
  16. 16. 5. Arterial blood gas analysis 6. Bedside tests : Peak expiratory flow (PEF), trans-cutaneous O2 (SpO2) and CO2 (tCO2) monitoring 7.   Tests for respiratory muscle function: PI max and PE max 8.   Tests for respiratory center function: CO2 stimulation test 9.   Tests for sleep related respiratory disorders: poly-somnography (PSG) However spirometry is the most basic and widely used method of evaluating pulmonary functions
  17. 17. Peak expiratory flow (PEF) is measured by a maximal forced expiration through Peak flow meter Correlates well with the FEV1 and is used as an estimate of airway caliber. PEFR should be measured regularly in asthmatics to monitor response to therapy and disease control.
  18. 18. Indications of spirometry • Diagnostic • Monitoring • Disability/impairment evaluations
  19. 19. Indications of spirometry • Diagnostic • To evaluate symptoms, signs or abnormal laboratory tests • To measure the effect of disease on pulmonary function • To screen individuals at risk of having pulmonary disease • To assess pre-operative risk • To assess prognosis • To assess health status before beginning strenuous physical activity programmes.
  20. 20. • Monitoring • To assess therapeutic intervention • To describe the course of diseases that affect lung function • To monitor people exposed to injurious agents • To monitor for adverse reactions to drugs with known pulmonary toxicity.
  21. 21. • Disability/impairment evaluations • To assess patients as part of a rehabilitation programme • To assess risks as part of an insurance evaluation • To assess individuals for legal reasons • Public health • Epidemiological surveys • Derivation of reference equations • Clinical research
  22. 22. Acceptable & reproducible criteria (ATS / ERS 2005 guidelines) • Acceptable criteria : a. Free from artefacts ( cough , glottis closure ) b. Free from leaks c. Good starts ( extrapolation back from the peak flow – “new time zero” should occur with in 5% / with in 150 ml.) d. Acceptable exhalation : (adults – 6 secs & a plateau& in children < 10yrs – 3 secs )
  23. 23. • Repeatability criteria : a. Three acceptable manoeuvers ( meeting above criteria ) b. The two largest FVC measurements with in 150 ml of each other c. The two largest FEV 1 measurements with in 150 ml of each other Upto 8 manoeuvers should be performed until criteria met
  24. 24. Performance of FVC maneuver • Check spirometer calibration. • Explain test. • Prepare patient. – Ask about smoking, recent illness, medication use, etc. (adapted from ATS/ ERS 2005 ) .
  25. 25. Performance of FVC maneuver (continued) • Give instructions and demonstrate: – Show nose clip and mouthpiece. – Demonstrate position of head with chin slightly elevated and neck somewhat extended. – Inhale as much as possible, put mouthpiece in mouth (open circuit), exhale as hard and fast as possible. – Give simple instructions.
  26. 26. spirometry
  27. 27. Information we get from a spirometer • A spirometer can be used to measure the following: – FVC and its derivatives (such as FEV1, FEF 25- 75%) – Forced inspiratory vital capacity (FIVC) – Peak expiratory flow rate – Maximum voluntary ventilation (MVV) – Slow VC – IC, IRV, and ERV – Pre and post bronchodilator studies
  28. 28. The spirometric recording is represented in 2 forms: absolute values and graphic forms – Flow-volume curve---flow meter measures flow rate in L/s upon exhalation; flow plotted as function of volume – Classic spirogram---volume as a function of time Volume F V C F E V 1 1 s e c o n d F E T T im e volume f l o w
  29. 29. Acceptable and Unacceptable Spirograms (from ATS, 1994) c o u g h 0 1 p o o r s ta r t 0 a c tu a l F V C n o t a t T L C p rio r to b lo w 0 Volume T im e g o o d e ffo rt 0 S u b m a x im a l e ffo rt 0 a c tu a l F V C p re m a tu re te rm in a tio n o r g lo ttic c lo s u re 0
  30. 30. Spirometry Interpretation: So what constitutes normal •Normal values vary and depend on: –Height –Age –Gender Ethnicity Spirometry can demonstrate two basic patterns of disorders
  31. 31. 1) obstructive pattern 2) Restrictive pattern Sometimes both patterns can be seen - mixed pattern
  32. 32. Obstructive Lung Disease — Differential Diagnosis  Asthma  COPD - chronic bronchitis - emphysema  Bronchiectasis  Bronchiolitis ( small airway diseases)  Upper airway obstruction
  33. 33. Obstructive Pattern • Decreased FEV1 • Decreased FVC • Decrease in FEV1> decrease in FVC • Decreased FEV1/FVC - <80% predicted • FEV1 used to follow severity in COPD
  34. 34. • FEV1/FVC • Interpretation of absolute value: >80 : Normal <79 : Abnormal
  35. 35. Spirogram in obs.. Airway disea… FEV1 / FVC < Normal Obs.. Lung D isease
  36. 36. Flow -volume loop in obs.. Airway diseases Mild OLD Moderate - Severe OLD
  37. 37. Obstructive Pattern — Evaluation  Spirometry  FEV1, FVC: decreased  FEV1/FVC: decreased (<80% predicted)  FV Loop “scooped”  Lung Volumes  TLC, RV: increased  Bronchodilator responsiveness
  38. 38. is the airway obstruction reversible? Bronchodilator response Asthma versus COPD • Degree to which FEV1 improves with inhaled bronchodilators. • Documents reversible airflow obstruction • Significant response if: - FEV1 increases by 12% and >200ml • Request if obstructive pattern on spirometry
  39. 39. • FEV1 improvement by • 12% and ≥ 200mL with • 200-400mcg Salbutamol by inhaler • or • 40-80mcg Ipratropium Bromide by inhaler Reversible airway disease diagnostic of asthma
  40. 40. Staging Severity of Asthma • Rule “60-80” • FEV1/FVC%<80% Severity FEV1 Intermittent Normal Mild persistent ≥ 80% Moderate persistent 60-80% Severe persistent ≤ 60%
  41. 41. Bronchial provocation test  Useful for diagnosis of asthma in the setting of normal pulmonary function tests  Common agents: - Methacholine, Histamine, others  Diagnostic if: ≥20% decrease in FEV1
  42. 42. Indications • History suggestive of bronchospasm induced by environmental or occupational agent in the setting of normal PFT • Cough Variant Asthma Contraindications and Precautions • Baseline FEV1/FVC% <70 • Recent upper respiratory tract infection • Recent influenza vaccination • Recent administration of bronchodilator • Ingestion of caffeine within 6 h before testing • Cold-air breathing, hyperventilation, exercise within 6 h before testing • Recent acute myocardial infarction or cerebrovascular accident, uncontrolled hypertension, or known aortic aneurysm
  43. 43. Restrictive Lung Disease — Differential Diagnosis  Pleural  Parenchymal  Chest wall  Neuromuscular
  44. 44. Restrictive Pattern  Decreased FEV1  Decreased FVC  FEV1/FVC normal or increased
  45. 45. Flow – volume loop & spirogram Reduced flow Miniature curve/ Witches hat
  46. 46. Restrictive Pattern – Evaluation  Spirometry  FVC, FEV1: decreased  FEV1/FVC: normal or increased  FV Loop “witch’s hat”/ miniature of curve  DLCO decreased  Lung Volumes  TLC, RV: decreased  Muscle pressures may be important
  47. 47. Grading of severity (Restriction) Severity FVC % predicted Mild 60-70% Moderate 50-60% Severe 35-49% Very Severe <35%
  48. 48. Mixed type • Low FEV1/ FVC – obstr • Reduced VC & TLC – restr • D/D – Sarcoidosis – Interstitial fibrosis – Lobar pneumonia or large pl effusion in COPD
  49. 49. Contraindications • Hemoptysis of unknown origin, • Pneumothorax, • Unstable angina pectoris, • Recent myocardial infarction • Thoracic aneurysms, • Abdominal aneurysms, • Cerebral aneurysmsRecent abdominal or thoracic surgical procedures • History of syncope associated with forced exhalation. • Recent eye surgery (increased intraocular pressure during forced expiration)
  50. 50. Activities that should preferably be avoided prior to lung function testing • Smoking within at least 6 h of testing • Consuming alcohol within 24 h of testing • Performing vigorous exercise within 30 min of testing • Wearing clothing that substantially restricts full chest and abdominal expansion • Eating a large meal within 2 h of testing • Short acting B2 agonists & anticholinergics -4 hours • Long acting B2 agonists – 12 hr • Oral methylxanthine -12 hours
  51. 51. Upper airway obstruction • Upper airway is the segment of conducting airways that extends between the nose ( during nasopharyngeal breathing) or mouth during oropharyngeal breathing) and the carina. • Fixed obstruction . • Variable intra-thoracic . • Variable extra-thoracic.
  52. 52. Fixed upper airway obstruction • Post-intubation stenosis • Large Goiters compressing the trachea • Endotracheal neoplasms • Stenosis of both main bronchi • Obstruction of the internal airway
  53. 53. Variable extrathoracic upper airway obstruction
  54. 54. Variable extrathoracic upper airway obstruction • Bilateral vocal cord palsy • Unilateral vocal cord palsy • Adhesions of vocal cord • Vocal cord constriction • Obstructive sleep apnea • Burns of nasopharynx
  55. 55. Variable intrathoracic upper airway obstruction • Obstruction of lower trachea • Obstruction of a main bronchus
  56. 56. Indices that show UAO in spirometry • Fixed obstruction: FEF50%/FIF50%=1 FEV1/FIV1=1 • Variable extra thoracic: FEF50%/FIF50%>2 FEV1/FIV1>1 • Variable intra thoracic: FEF50%/FIF50%<1 ( even 0.3) FEV1/FIV1<1
  57. 57. F-V loop in Upper Airway Obstruction normal
  58. 58. EMPEY index • It is the ratio of FEV1 to PEF • The best indicator in large airways obstruction • Significant value is greater than 8 • The higher the index the more severe the obstruction • As a clinical screen in the absence of a flow-volume loop it is a reasonable guide to the presence of UAO
  59. 59. Lung volumes • Measurement: - helium dilution method - nitrogen washout - body plethysmography • Indications: - Diagnose restrictive component - Differentiate chronic bronchitis from emphysema
  60. 60. • 4 volumes: inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume • 2 or more volumes comprise a capacity. • 4 capacites: vital capacity, inspiratory capacity, functional residual capacity, and total lung capacity
  61. 61. • Functional Residual Capacity (FRC): – Sum of RV and ERV or the volume of air in the lungs at end-expiratory tidal position – Measured with multiple- breath closed-circuit helium dilution, multiple- breath open-circuit nitrogen washout, or body plethysmography (not by spirometry)
  62. 62. Lung volume patterns • Obstructive - TLC > 120% predicted - RV > 120% predicted • Restrictive - TLC < 80% predicted - RV < 80% predicted
  63. 63. Diffusion capacity • Diffusing capacity of lungs for CO • Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries • Depends on: - alveolar—capillary membrane - hemoglobin concentration - cardiac output
  64. 64. Alveolo – capillary membrane • Gas diffuses across this alveolar-capillary barrier. • This barrier is as thin as 0.3 μm in some places and has a surface area of 50-100 square meters!
  65. 65. Normal lung parenchyma
  66. 66. Decreased DLCO (<80% predicted) • Obstructive lung disease • Parenchymal disease • Pulmonary vascular disease • Anemia • Lung resection Increased DLCO (>120-140% predicted) • Asthma (or normal) • Pulmonary hemorrhage • Polycythemia • Left to right intra cardiac shunts • Obesity, exercise , supine po Isolated DLCO decrease : primary PAH ,recurrent pulmonary emboli , obliterative -vasculopathy
  67. 67. Emphysematous lung parenchyma
  68. 68. Thickned interstitium in IPF
  69. 69. DLCO - indications  Differentiate asthma from emphysema  Evaluation and severity of restrictive lung disease  Early stages of pulmonary hypertension • Expensive!
  70. 70. 70% 80% MIXED OBSTRUCTIVE & RESTRICTIVE LUNG DISEASE RESTRICTIVE LUNG DISEASE OBSTRUCTIVE LUNG DISEASESE FEV1 / FVC %age FVC (%age predicted) 100% 100% NORMAL
  71. 71. Approach to interpreting commonly performed PFT
  72. 72. Pre-operative Evaluation For Surgery Other Than Pulmonary Resection High Risk Moderate Risk 75% FEV1 FVC 50% 25% 75% Low Risk “Normal risk” 25% 50%
  73. 73. Pre-operative Risk Assessment For Pulmonary Resection Surgery • Calculate predicted post operative (ppo) FEV1 • For pneumonectomy, predicted P.O FEV1 = preoperative FEV1 X % perfusion to remaining lung (regional quantitative perfusion scans may be used) • For lobectomy, Predicted P.O. FEV1 = preoperative FEV1 X no of lung segments remaing after resection /total no segments in both lungs • Using “Rule of Five” • FEV1 > 1L makes patient suitable for any lung resection surgery
  74. 74. Spirometry interpretation ?
  75. 75. Case 1: Spirometry interpretation
  76. 76. Diagnosis?
  77. 77. Spirometry Report
  78. 78. Severe obstruction with bronchodilator test positive
  79. 79. 1. Acceptable exhalation in children <10 years in spirometry a. 3 Secs b. 6 Secs c. 9 Secs d. None
  80. 80. 2. Flow volume curve shows a. Poor effort b. bronchial asthma c. Emphysema d. ILD
  81. 81. 3.Conditions that cause isolated decrease in DLCO a. Pulmonary thromboembolism b. Pulmonary hypertension c. Vasculitis d. Scleroderma e. Early ILD f. all
  82. 82. Case 2  49 y/o Female Shortness of breath and nonproductive cough  FEV1/FVC: 85%  FVC: 1.17 L (34%)  FEV1: 1.00 L (37%)  VC: 1.17 L (34%) a.Pulmonary fibrosis b. Br.asthma c.COPD C. None

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